Shale reservoirs throughout the world are known to contain enormous quantities of gaseous and liquid hydrocarbons. However, some aspects of the production mechanisms operative in these reservoirs are not well understood. Until fairly recently, the wettability of gas reservoirs has not been of much concern. With the exploitation of gas reserves in coal seams and shales, the so-called unconventional reservoirs, the question of wettability takes on much greater importance.
In order to develop methods to efficiently recover gas from a shale reservoir, it is very useful to gain a good understanding of the chemical nature of the shale. A productive exploitation of the shale reservoir will likely require the introduction of a fluid into the reservoir. Therefore, how that fluid interacts with the formation material is to a great degree determined by the extent to which the fluid wets the formation. Reliable test methods have been developed to measure the wettability of a material, but the methods are often beyond the capabilities of most field laboratories. Thus, it is desirable in cases hydrocarbon recovery from unconventional reservoirs such as coal seams and shale reservoirs to have improved techniques for understanding the wettability characteristics of the reservoir material that can be carried out quickly, simply and can be made in a field setting.